Ornamental · Poaceae
Annual Ryegrass
Lolium multiflorum
Sow it in fall and annual ryegrass delivers fast cover, hungry roots, and a stand that mostly bows out by spring.
Full sun
Every 3–7 days
50–120 days
USDA 6–9
Overview
When ground needs covering in a hurry, annual ryegrass jumps to the front of the line. It is a cool-season bunchgrass from the genus Lolium, flashing bright, glossy leaves, and it germinates and roots faster than almost anything else you can sow. Gardeners and farmers put it to work to hold soil over winter, soak up leftover nitrogen, and feed grazing animals.
Just keep it straight from cereal rye and from its perennial cousin. This is a true annual that blazes through its whole life in one season, shooting up flower spikes in spring and dying back the moment heat or cold arrives. That short life pays off, since a cover crop that wraps up on its own saves you a termination pass.
The trait to stay on top of is its drive to spread. Annual ryegrass sets seed heavily and can be stubborn to kill, so it slips into fields and margins as a weedy volunteer if a stand matures. Time it well and it works hard for you; ignore it and it works against you.
Care
The short version: sow it shallow into moist soil in full sun, keep it watered while it establishes, and it tackles most soils on its own. Mow no closer than 3 to 4 inches, and end it at early bloom before it seeds.
Light
Annual ryegrass thrives in full sun yet takes partial shade in stride. Pile on the light and the stand comes in thicker and faster, exactly what a cover crop wants as it races to blanket bare ground.
Water
It runs on steady soil moisture to germinate fast and establish, and it sulks the moment things dry out. Sustained heat and drought will finish it off, though it shrugs off wet and even briefly flooded soil better than most cover crops.
Soil
Few grasses take ground this easily. It powers into clay, loam, sand, rocky, and high-organic soils across a wide pH of 5.0 to 7.5, though it really hits its stride in rich, moist, well-drained loam.
Temperature
This is a cold-tolerant grass that runs from about 10°F to 81°F (-12°C to 27°C). It loves cool weather and pulls back once summer heat lands, which is exactly why it gets sown for fall and spring.
Humidity
Outdoor humidity simply does not register, so there is no figure to chase. What carries the day is moisture in the soil, the fuel behind its quick germination and early surge of growth.
Feeding
Most of the time it wants no feeding at all, scavenging leftover soil nitrogen instead of living off fertilizer. Toss in a nitrogen source at planting only on genuinely poor soils.
Pruning
Mow to keep it as living mulch or temporary turf, but never closer than 3 to 4 inches. When you are finished with it, terminate at early bloom by mowing, tilling, or a contact herbicide, since mowing alone may not finish off an established stand.
Repotting
none
Size & spacing
Sown as a stand rather than spaced plants, it shoots up 1 to 3 feet (30 to 91 cm) tall, with each plant claiming only about 8 to 12 inches (20 to 30 cm). The seeding rate, not spacing, drives the density you get.
When to plant
Annual ryegrass is a cool-season grass, so it hits its stride in the shoulders of the year, not the heat of summer. Direct sow it from late summer into fall to overwinter in mild zones, or jump on early spring, and in cold country get it down at least 40 days before the first killing frost. Flower spikes shoot up in spring, your cue to terminate before seed sets.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: not typically started indoors; direct sown
- Plant: Late summer to early fall (late July through October) for overwintering in mild zones, or early spring; in zone 5 and colder sow at least 40 days before first killing frost
- Harvest: Flower spikes in spring; terminate before seed set. As a cover crop, biomass is produced over fall, winter and spring.
Hardiness
USDA hardiness zones: 6–9
Temperature: down to -23°C
Troubleshooting
Trouble with annual ryegrass leans on timing and control far more than disease. The big risks are letting it seed, losing a stand to winter or drought, and a thin start from dry ground. Match what you spot below and jump on it before a small problem spreads into the next crop.
It bounces back as a volunteer
Let a stand flower and finish its seed, and next season inherits a real chore. One plant flings out around 300 seeds that come up with ease, and a mower alone will not put it down, all the more so where some populations shake off glyphosate. Beat it to the punch and terminate at early bloom by disking, plowing, or hitting it with a contact herbicide before any seedheads ripen.
Fix:
- Terminate at early bloom before seed set by disking, plowing, or a non-persistent contact herbicide
- Use a chaff/seed collection system at harvest if grown to seed nearby
- Repeat control passes since seeds germinate in both fall and spring across a wide temperature range (36 to 104 degrees F)
Brown gaps tear open over winter
Those gaps usually spell winterkill, and it strikes hardest in zone 5 and colder where no snow tucks the crowns in. Push past about 80°F (27°C) with summer heat and drought and a stand thins out the very same way. Get seed down early so roots dig in before the cold, at least 40 days ahead of the first killing frost, or lean into the dieback as a free, self-clearing cover when that was the whole plan.
Fix:
- Reseed bare areas in mild zones, or accept winterkill where a self-terminating cover is desired
- Plant early enough (at least 40 days before first killing frost) so plants establish before cold
Patchy, thin stand right after sowing
Track it down and dry soil is almost always the answer, because the seed runs on steady moisture to leap up fast, and seed buried too deep cannot fight its way to the light. Sow it shallow at 1/4 to 1/2 inch deep, and water it in the moment rain falls short. Lock in a smart rate too, around 10 to 20 lb per acre drilled or 20 to 30 lb broadcast, and watch the bare spots knit shut.
Fix:
- Sow at 1/4 to 1/2 inch depth and ensure rainfall or irrigation for good establishment
- Use proper seeding rates (10-20 lb/acre drilled, 20-30 lb/acre broadcast)
Toxicity
As a lawn or cover crop, annual ryegrass is safe around cats and dogs, who at worst get a mild upset stomach from chewing grass. The real flag goes up for horses and grazing livestock: ryegrass carrying fungal endophytes packs alkaloids that bring on ryegrass staggers, a tremor and incoordination syndrome. Graze or cut it before the seedheads form.
Toxic to
Horses · Rabbits · Livestock · Birds · People
Safe for
Cats · Dogs
Horses Moderate
Horses call for real care here, because grazing endophyte-infected ryegrass can spark ryegrass staggers: muscle tremors, a stiff or jerky gait, and stumbling that flares the instant the horse is stressed or asked to move. Ergot alkaloids in the seedheads clamp down on the blood vessels too.
Rabbits Caution
Plain ryegrass is everyday rabbit fare, but the same fungal alkaloids that hit grazing livestock can stack up in older, seedy growth. Steer rabbits clear of heading or endophyte-affected stands and hand them young, clean grass instead.
Livestock Moderate
Cattle, sheep, and goats grazing affected pasture can catch the same staggers from lolitrem B, trembling and going down when they fire up or try to run. The ergovaline riding along squeezes the blood vessels and drags on their performance.
Birds Caution
Ryegrass seed turns up across heaps of bird diets and counts as no known poison. The one catch is ergot in mature seedheads, so it pays to keep birds from gorging on heavy, fungus-marked grain.
People Caution
No part of this grass is built for eating, so there is nothing here to bring to the table. For people the real nuisance is the pollen, that famous spark of hay fever in late spring.
Cats None
Cats can roam it freely, since the grass packs no toxin and the ASPCA flags no danger for it. A curious nibbler might cough a blade back up, and that is genuinely where the story ends.
Dogs None
Dogs get to romp across it as a lawn or cover crop without a worry. A mouthful of the leaves stirs up nothing worse than the mild, here-then-gone tummy upset any grass can.
Safe as a lawn, forage, or cover-crop grass around pets; the foliage itself is non-toxic to cats and dogs. For pastured horses and livestock, manage endophyte- and ergot-affected seedheads - cut or graze before heading and avoid feeding affected, mature ryegrass.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
Poison Control: (800) 222-1222
Canada
Poison Centres: 1-844-764-7669
Varieties
A handful of distinct types charge under the ryegrass name, and they each play their own game. These are the ones worth telling apart before you grab seed.
Annual / Italian ryegrass (Lolium multiflorum)
This is the speedy cover-crop and forage type, a short-lived cool-season bunchgrass that flashes bright, glossy leaves and usually winterkills in cold zones.
Perennial ryegrass (Lolium perenne)
A close relative grown for turf and pasture that charges back year after year, unlike the annual Lolium multiflorum that bows out each season.
Westerwolds annual ryegrass
A true-annual form of Lolium multiflorum that races to flower and set seed in its very first season without a cold spell, prized for fast, single-season cover or forage.
Diploid vs tetraploid types
Tetraploid cultivars pack doubled chromosomes that hand them larger, juicier leaves and seeds and better palatability, while diploids pile into denser, finer stands.
How to propagate
Annual ryegrass grows one easy way, from seed sown straight into the ground, and it could hardly ask less of you.
SeedEasy
Late summer to early fall for overwintering, or early spring; sow at least 40 days before first killing frost in cold zones · Germinates and establishes very quickly, often within 1-2 weeks in moist cool soil
Growing this one is a breeze: just sow seed straight into the ground, never indoors. Drop it in late summer to early fall to overwinter it, or in early spring, and in cold zones get it down at least 40 days before the first killing frost. Broadcast at 20 to 30 lb per acre or drill at 10 to 20 lb per acre, only 1/4 to 1/2 inch deep, into moist soil, then watch it sprout and grab hold within a week or two.
Myths
Annual ryegrass is the same plant as cereal rye.
They grab a word from each other's names and share nothing more. Annual ryegrass is Lolium multiflorum, a fine-leaved forage and turf bunchgrass, while cereal rye is Secale cereale, the tall, fiercely cold-hardy grain that turns into bread. Two different grasses from two different genera, so the seed and growing know-how for one just will not carry over to the other.